shmem.c revision 3fcfab16c5b86eaa3db3a9a31adba550c5b67141
1/* 2 * Resizable virtual memory filesystem for Linux. 3 * 4 * Copyright (C) 2000 Linus Torvalds. 5 * 2000 Transmeta Corp. 6 * 2000-2001 Christoph Rohland 7 * 2000-2001 SAP AG 8 * 2002 Red Hat Inc. 9 * Copyright (C) 2002-2005 Hugh Dickins. 10 * Copyright (C) 2002-2005 VERITAS Software Corporation. 11 * Copyright (C) 2004 Andi Kleen, SuSE Labs 12 * 13 * Extended attribute support for tmpfs: 14 * Copyright (c) 2004, Luke Kenneth Casson Leighton <lkcl@lkcl.net> 15 * Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com> 16 * 17 * This file is released under the GPL. 18 */ 19 20/* 21 * This virtual memory filesystem is heavily based on the ramfs. It 22 * extends ramfs by the ability to use swap and honor resource limits 23 * which makes it a completely usable filesystem. 24 */ 25 26#include <linux/module.h> 27#include <linux/init.h> 28#include <linux/fs.h> 29#include <linux/xattr.h> 30#include <linux/generic_acl.h> 31#include <linux/mm.h> 32#include <linux/mman.h> 33#include <linux/file.h> 34#include <linux/swap.h> 35#include <linux/pagemap.h> 36#include <linux/string.h> 37#include <linux/slab.h> 38#include <linux/backing-dev.h> 39#include <linux/shmem_fs.h> 40#include <linux/mount.h> 41#include <linux/writeback.h> 42#include <linux/vfs.h> 43#include <linux/blkdev.h> 44#include <linux/security.h> 45#include <linux/swapops.h> 46#include <linux/mempolicy.h> 47#include <linux/namei.h> 48#include <linux/ctype.h> 49#include <linux/migrate.h> 50#include <linux/highmem.h> 51#include <linux/backing-dev.h> 52 53#include <asm/uaccess.h> 54#include <asm/div64.h> 55#include <asm/pgtable.h> 56 57/* This magic number is used in glibc for posix shared memory */ 58#define TMPFS_MAGIC 0x01021994 59 60#define ENTRIES_PER_PAGE (PAGE_CACHE_SIZE/sizeof(unsigned long)) 61#define ENTRIES_PER_PAGEPAGE (ENTRIES_PER_PAGE*ENTRIES_PER_PAGE) 62#define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512) 63 64#define SHMEM_MAX_INDEX (SHMEM_NR_DIRECT + (ENTRIES_PER_PAGEPAGE/2) * (ENTRIES_PER_PAGE+1)) 65#define SHMEM_MAX_BYTES ((unsigned long long)SHMEM_MAX_INDEX << PAGE_CACHE_SHIFT) 66 67#define VM_ACCT(size) (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT) 68 69/* info->flags needs VM_flags to handle pagein/truncate races efficiently */ 70#define SHMEM_PAGEIN VM_READ 71#define SHMEM_TRUNCATE VM_WRITE 72 73/* Definition to limit shmem_truncate's steps between cond_rescheds */ 74#define LATENCY_LIMIT 64 75 76/* Pretend that each entry is of this size in directory's i_size */ 77#define BOGO_DIRENT_SIZE 20 78 79/* Flag allocation requirements to shmem_getpage and shmem_swp_alloc */ 80enum sgp_type { 81 SGP_QUICK, /* don't try more than file page cache lookup */ 82 SGP_READ, /* don't exceed i_size, don't allocate page */ 83 SGP_CACHE, /* don't exceed i_size, may allocate page */ 84 SGP_WRITE, /* may exceed i_size, may allocate page */ 85}; 86 87static int shmem_getpage(struct inode *inode, unsigned long idx, 88 struct page **pagep, enum sgp_type sgp, int *type); 89 90static inline struct page *shmem_dir_alloc(gfp_t gfp_mask) 91{ 92 /* 93 * The above definition of ENTRIES_PER_PAGE, and the use of 94 * BLOCKS_PER_PAGE on indirect pages, assume PAGE_CACHE_SIZE: 95 * might be reconsidered if it ever diverges from PAGE_SIZE. 96 */ 97 return alloc_pages(gfp_mask, PAGE_CACHE_SHIFT-PAGE_SHIFT); 98} 99 100static inline void shmem_dir_free(struct page *page) 101{ 102 __free_pages(page, PAGE_CACHE_SHIFT-PAGE_SHIFT); 103} 104 105static struct page **shmem_dir_map(struct page *page) 106{ 107 return (struct page **)kmap_atomic(page, KM_USER0); 108} 109 110static inline void shmem_dir_unmap(struct page **dir) 111{ 112 kunmap_atomic(dir, KM_USER0); 113} 114 115static swp_entry_t *shmem_swp_map(struct page *page) 116{ 117 return (swp_entry_t *)kmap_atomic(page, KM_USER1); 118} 119 120static inline void shmem_swp_balance_unmap(void) 121{ 122 /* 123 * When passing a pointer to an i_direct entry, to code which 124 * also handles indirect entries and so will shmem_swp_unmap, 125 * we must arrange for the preempt count to remain in balance. 126 * What kmap_atomic of a lowmem page does depends on config 127 * and architecture, so pretend to kmap_atomic some lowmem page. 128 */ 129 (void) kmap_atomic(ZERO_PAGE(0), KM_USER1); 130} 131 132static inline void shmem_swp_unmap(swp_entry_t *entry) 133{ 134 kunmap_atomic(entry, KM_USER1); 135} 136 137static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb) 138{ 139 return sb->s_fs_info; 140} 141 142/* 143 * shmem_file_setup pre-accounts the whole fixed size of a VM object, 144 * for shared memory and for shared anonymous (/dev/zero) mappings 145 * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1), 146 * consistent with the pre-accounting of private mappings ... 147 */ 148static inline int shmem_acct_size(unsigned long flags, loff_t size) 149{ 150 return (flags & VM_ACCOUNT)? 151 security_vm_enough_memory(VM_ACCT(size)): 0; 152} 153 154static inline void shmem_unacct_size(unsigned long flags, loff_t size) 155{ 156 if (flags & VM_ACCOUNT) 157 vm_unacct_memory(VM_ACCT(size)); 158} 159 160/* 161 * ... whereas tmpfs objects are accounted incrementally as 162 * pages are allocated, in order to allow huge sparse files. 163 * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM, 164 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM. 165 */ 166static inline int shmem_acct_block(unsigned long flags) 167{ 168 return (flags & VM_ACCOUNT)? 169 0: security_vm_enough_memory(VM_ACCT(PAGE_CACHE_SIZE)); 170} 171 172static inline void shmem_unacct_blocks(unsigned long flags, long pages) 173{ 174 if (!(flags & VM_ACCOUNT)) 175 vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE)); 176} 177 178static struct super_operations shmem_ops; 179static const struct address_space_operations shmem_aops; 180static struct file_operations shmem_file_operations; 181static struct inode_operations shmem_inode_operations; 182static struct inode_operations shmem_dir_inode_operations; 183static struct inode_operations shmem_special_inode_operations; 184static struct vm_operations_struct shmem_vm_ops; 185 186static struct backing_dev_info shmem_backing_dev_info __read_mostly = { 187 .ra_pages = 0, /* No readahead */ 188 .capabilities = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK, 189 .unplug_io_fn = default_unplug_io_fn, 190}; 191 192static LIST_HEAD(shmem_swaplist); 193static DEFINE_SPINLOCK(shmem_swaplist_lock); 194 195static void shmem_free_blocks(struct inode *inode, long pages) 196{ 197 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 198 if (sbinfo->max_blocks) { 199 spin_lock(&sbinfo->stat_lock); 200 sbinfo->free_blocks += pages; 201 inode->i_blocks -= pages*BLOCKS_PER_PAGE; 202 spin_unlock(&sbinfo->stat_lock); 203 } 204} 205 206/* 207 * shmem_recalc_inode - recalculate the size of an inode 208 * 209 * @inode: inode to recalc 210 * 211 * We have to calculate the free blocks since the mm can drop 212 * undirtied hole pages behind our back. 213 * 214 * But normally info->alloced == inode->i_mapping->nrpages + info->swapped 215 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped) 216 * 217 * It has to be called with the spinlock held. 218 */ 219static void shmem_recalc_inode(struct inode *inode) 220{ 221 struct shmem_inode_info *info = SHMEM_I(inode); 222 long freed; 223 224 freed = info->alloced - info->swapped - inode->i_mapping->nrpages; 225 if (freed > 0) { 226 info->alloced -= freed; 227 shmem_unacct_blocks(info->flags, freed); 228 shmem_free_blocks(inode, freed); 229 } 230} 231 232/* 233 * shmem_swp_entry - find the swap vector position in the info structure 234 * 235 * @info: info structure for the inode 236 * @index: index of the page to find 237 * @page: optional page to add to the structure. Has to be preset to 238 * all zeros 239 * 240 * If there is no space allocated yet it will return NULL when 241 * page is NULL, else it will use the page for the needed block, 242 * setting it to NULL on return to indicate that it has been used. 243 * 244 * The swap vector is organized the following way: 245 * 246 * There are SHMEM_NR_DIRECT entries directly stored in the 247 * shmem_inode_info structure. So small files do not need an addional 248 * allocation. 249 * 250 * For pages with index > SHMEM_NR_DIRECT there is the pointer 251 * i_indirect which points to a page which holds in the first half 252 * doubly indirect blocks, in the second half triple indirect blocks: 253 * 254 * For an artificial ENTRIES_PER_PAGE = 4 this would lead to the 255 * following layout (for SHMEM_NR_DIRECT == 16): 256 * 257 * i_indirect -> dir --> 16-19 258 * | +-> 20-23 259 * | 260 * +-->dir2 --> 24-27 261 * | +-> 28-31 262 * | +-> 32-35 263 * | +-> 36-39 264 * | 265 * +-->dir3 --> 40-43 266 * +-> 44-47 267 * +-> 48-51 268 * +-> 52-55 269 */ 270static swp_entry_t *shmem_swp_entry(struct shmem_inode_info *info, unsigned long index, struct page **page) 271{ 272 unsigned long offset; 273 struct page **dir; 274 struct page *subdir; 275 276 if (index < SHMEM_NR_DIRECT) { 277 shmem_swp_balance_unmap(); 278 return info->i_direct+index; 279 } 280 if (!info->i_indirect) { 281 if (page) { 282 info->i_indirect = *page; 283 *page = NULL; 284 } 285 return NULL; /* need another page */ 286 } 287 288 index -= SHMEM_NR_DIRECT; 289 offset = index % ENTRIES_PER_PAGE; 290 index /= ENTRIES_PER_PAGE; 291 dir = shmem_dir_map(info->i_indirect); 292 293 if (index >= ENTRIES_PER_PAGE/2) { 294 index -= ENTRIES_PER_PAGE/2; 295 dir += ENTRIES_PER_PAGE/2 + index/ENTRIES_PER_PAGE; 296 index %= ENTRIES_PER_PAGE; 297 subdir = *dir; 298 if (!subdir) { 299 if (page) { 300 *dir = *page; 301 *page = NULL; 302 } 303 shmem_dir_unmap(dir); 304 return NULL; /* need another page */ 305 } 306 shmem_dir_unmap(dir); 307 dir = shmem_dir_map(subdir); 308 } 309 310 dir += index; 311 subdir = *dir; 312 if (!subdir) { 313 if (!page || !(subdir = *page)) { 314 shmem_dir_unmap(dir); 315 return NULL; /* need a page */ 316 } 317 *dir = subdir; 318 *page = NULL; 319 } 320 shmem_dir_unmap(dir); 321 return shmem_swp_map(subdir) + offset; 322} 323 324static void shmem_swp_set(struct shmem_inode_info *info, swp_entry_t *entry, unsigned long value) 325{ 326 long incdec = value? 1: -1; 327 328 entry->val = value; 329 info->swapped += incdec; 330 if ((unsigned long)(entry - info->i_direct) >= SHMEM_NR_DIRECT) { 331 struct page *page = kmap_atomic_to_page(entry); 332 set_page_private(page, page_private(page) + incdec); 333 } 334} 335 336/* 337 * shmem_swp_alloc - get the position of the swap entry for the page. 338 * If it does not exist allocate the entry. 339 * 340 * @info: info structure for the inode 341 * @index: index of the page to find 342 * @sgp: check and recheck i_size? skip allocation? 343 */ 344static swp_entry_t *shmem_swp_alloc(struct shmem_inode_info *info, unsigned long index, enum sgp_type sgp) 345{ 346 struct inode *inode = &info->vfs_inode; 347 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 348 struct page *page = NULL; 349 swp_entry_t *entry; 350 351 if (sgp != SGP_WRITE && 352 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) 353 return ERR_PTR(-EINVAL); 354 355 while (!(entry = shmem_swp_entry(info, index, &page))) { 356 if (sgp == SGP_READ) 357 return shmem_swp_map(ZERO_PAGE(0)); 358 /* 359 * Test free_blocks against 1 not 0, since we have 1 data 360 * page (and perhaps indirect index pages) yet to allocate: 361 * a waste to allocate index if we cannot allocate data. 362 */ 363 if (sbinfo->max_blocks) { 364 spin_lock(&sbinfo->stat_lock); 365 if (sbinfo->free_blocks <= 1) { 366 spin_unlock(&sbinfo->stat_lock); 367 return ERR_PTR(-ENOSPC); 368 } 369 sbinfo->free_blocks--; 370 inode->i_blocks += BLOCKS_PER_PAGE; 371 spin_unlock(&sbinfo->stat_lock); 372 } 373 374 spin_unlock(&info->lock); 375 page = shmem_dir_alloc(mapping_gfp_mask(inode->i_mapping) | __GFP_ZERO); 376 if (page) 377 set_page_private(page, 0); 378 spin_lock(&info->lock); 379 380 if (!page) { 381 shmem_free_blocks(inode, 1); 382 return ERR_PTR(-ENOMEM); 383 } 384 if (sgp != SGP_WRITE && 385 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) { 386 entry = ERR_PTR(-EINVAL); 387 break; 388 } 389 if (info->next_index <= index) 390 info->next_index = index + 1; 391 } 392 if (page) { 393 /* another task gave its page, or truncated the file */ 394 shmem_free_blocks(inode, 1); 395 shmem_dir_free(page); 396 } 397 if (info->next_index <= index && !IS_ERR(entry)) 398 info->next_index = index + 1; 399 return entry; 400} 401 402/* 403 * shmem_free_swp - free some swap entries in a directory 404 * 405 * @dir: pointer to the directory 406 * @edir: pointer after last entry of the directory 407 */ 408static int shmem_free_swp(swp_entry_t *dir, swp_entry_t *edir) 409{ 410 swp_entry_t *ptr; 411 int freed = 0; 412 413 for (ptr = dir; ptr < edir; ptr++) { 414 if (ptr->val) { 415 free_swap_and_cache(*ptr); 416 *ptr = (swp_entry_t){0}; 417 freed++; 418 } 419 } 420 return freed; 421} 422 423static int shmem_map_and_free_swp(struct page *subdir, 424 int offset, int limit, struct page ***dir) 425{ 426 swp_entry_t *ptr; 427 int freed = 0; 428 429 ptr = shmem_swp_map(subdir); 430 for (; offset < limit; offset += LATENCY_LIMIT) { 431 int size = limit - offset; 432 if (size > LATENCY_LIMIT) 433 size = LATENCY_LIMIT; 434 freed += shmem_free_swp(ptr+offset, ptr+offset+size); 435 if (need_resched()) { 436 shmem_swp_unmap(ptr); 437 if (*dir) { 438 shmem_dir_unmap(*dir); 439 *dir = NULL; 440 } 441 cond_resched(); 442 ptr = shmem_swp_map(subdir); 443 } 444 } 445 shmem_swp_unmap(ptr); 446 return freed; 447} 448 449static void shmem_free_pages(struct list_head *next) 450{ 451 struct page *page; 452 int freed = 0; 453 454 do { 455 page = container_of(next, struct page, lru); 456 next = next->next; 457 shmem_dir_free(page); 458 freed++; 459 if (freed >= LATENCY_LIMIT) { 460 cond_resched(); 461 freed = 0; 462 } 463 } while (next); 464} 465 466static void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end) 467{ 468 struct shmem_inode_info *info = SHMEM_I(inode); 469 unsigned long idx; 470 unsigned long size; 471 unsigned long limit; 472 unsigned long stage; 473 unsigned long diroff; 474 struct page **dir; 475 struct page *topdir; 476 struct page *middir; 477 struct page *subdir; 478 swp_entry_t *ptr; 479 LIST_HEAD(pages_to_free); 480 long nr_pages_to_free = 0; 481 long nr_swaps_freed = 0; 482 int offset; 483 int freed; 484 int punch_hole = 0; 485 486 inode->i_ctime = inode->i_mtime = CURRENT_TIME; 487 idx = (start + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; 488 if (idx >= info->next_index) 489 return; 490 491 spin_lock(&info->lock); 492 info->flags |= SHMEM_TRUNCATE; 493 if (likely(end == (loff_t) -1)) { 494 limit = info->next_index; 495 info->next_index = idx; 496 } else { 497 limit = (end + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; 498 if (limit > info->next_index) 499 limit = info->next_index; 500 punch_hole = 1; 501 } 502 503 topdir = info->i_indirect; 504 if (topdir && idx <= SHMEM_NR_DIRECT && !punch_hole) { 505 info->i_indirect = NULL; 506 nr_pages_to_free++; 507 list_add(&topdir->lru, &pages_to_free); 508 } 509 spin_unlock(&info->lock); 510 511 if (info->swapped && idx < SHMEM_NR_DIRECT) { 512 ptr = info->i_direct; 513 size = limit; 514 if (size > SHMEM_NR_DIRECT) 515 size = SHMEM_NR_DIRECT; 516 nr_swaps_freed = shmem_free_swp(ptr+idx, ptr+size); 517 } 518 if (!topdir) 519 goto done2; 520 521 BUG_ON(limit <= SHMEM_NR_DIRECT); 522 limit -= SHMEM_NR_DIRECT; 523 idx = (idx > SHMEM_NR_DIRECT)? (idx - SHMEM_NR_DIRECT): 0; 524 offset = idx % ENTRIES_PER_PAGE; 525 idx -= offset; 526 527 dir = shmem_dir_map(topdir); 528 stage = ENTRIES_PER_PAGEPAGE/2; 529 if (idx < ENTRIES_PER_PAGEPAGE/2) { 530 middir = topdir; 531 diroff = idx/ENTRIES_PER_PAGE; 532 } else { 533 dir += ENTRIES_PER_PAGE/2; 534 dir += (idx - ENTRIES_PER_PAGEPAGE/2)/ENTRIES_PER_PAGEPAGE; 535 while (stage <= idx) 536 stage += ENTRIES_PER_PAGEPAGE; 537 middir = *dir; 538 if (*dir) { 539 diroff = ((idx - ENTRIES_PER_PAGEPAGE/2) % 540 ENTRIES_PER_PAGEPAGE) / ENTRIES_PER_PAGE; 541 if (!diroff && !offset) { 542 *dir = NULL; 543 nr_pages_to_free++; 544 list_add(&middir->lru, &pages_to_free); 545 } 546 shmem_dir_unmap(dir); 547 dir = shmem_dir_map(middir); 548 } else { 549 diroff = 0; 550 offset = 0; 551 idx = stage; 552 } 553 } 554 555 for (; idx < limit; idx += ENTRIES_PER_PAGE, diroff++) { 556 if (unlikely(idx == stage)) { 557 shmem_dir_unmap(dir); 558 dir = shmem_dir_map(topdir) + 559 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE; 560 while (!*dir) { 561 dir++; 562 idx += ENTRIES_PER_PAGEPAGE; 563 if (idx >= limit) 564 goto done1; 565 } 566 stage = idx + ENTRIES_PER_PAGEPAGE; 567 middir = *dir; 568 *dir = NULL; 569 nr_pages_to_free++; 570 list_add(&middir->lru, &pages_to_free); 571 shmem_dir_unmap(dir); 572 cond_resched(); 573 dir = shmem_dir_map(middir); 574 diroff = 0; 575 } 576 subdir = dir[diroff]; 577 if (subdir && page_private(subdir)) { 578 size = limit - idx; 579 if (size > ENTRIES_PER_PAGE) 580 size = ENTRIES_PER_PAGE; 581 freed = shmem_map_and_free_swp(subdir, 582 offset, size, &dir); 583 if (!dir) 584 dir = shmem_dir_map(middir); 585 nr_swaps_freed += freed; 586 if (offset) 587 spin_lock(&info->lock); 588 set_page_private(subdir, page_private(subdir) - freed); 589 if (offset) 590 spin_unlock(&info->lock); 591 if (!punch_hole) 592 BUG_ON(page_private(subdir) > offset); 593 } 594 if (offset) 595 offset = 0; 596 else if (subdir && !page_private(subdir)) { 597 dir[diroff] = NULL; 598 nr_pages_to_free++; 599 list_add(&subdir->lru, &pages_to_free); 600 } 601 } 602done1: 603 shmem_dir_unmap(dir); 604done2: 605 if (inode->i_mapping->nrpages && (info->flags & SHMEM_PAGEIN)) { 606 /* 607 * Call truncate_inode_pages again: racing shmem_unuse_inode 608 * may have swizzled a page in from swap since vmtruncate or 609 * generic_delete_inode did it, before we lowered next_index. 610 * Also, though shmem_getpage checks i_size before adding to 611 * cache, no recheck after: so fix the narrow window there too. 612 */ 613 truncate_inode_pages_range(inode->i_mapping, start, end); 614 } 615 616 spin_lock(&info->lock); 617 info->flags &= ~SHMEM_TRUNCATE; 618 info->swapped -= nr_swaps_freed; 619 if (nr_pages_to_free) 620 shmem_free_blocks(inode, nr_pages_to_free); 621 shmem_recalc_inode(inode); 622 spin_unlock(&info->lock); 623 624 /* 625 * Empty swap vector directory pages to be freed? 626 */ 627 if (!list_empty(&pages_to_free)) { 628 pages_to_free.prev->next = NULL; 629 shmem_free_pages(pages_to_free.next); 630 } 631} 632 633static void shmem_truncate(struct inode *inode) 634{ 635 shmem_truncate_range(inode, inode->i_size, (loff_t)-1); 636} 637 638static int shmem_notify_change(struct dentry *dentry, struct iattr *attr) 639{ 640 struct inode *inode = dentry->d_inode; 641 struct page *page = NULL; 642 int error; 643 644 if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) { 645 if (attr->ia_size < inode->i_size) { 646 /* 647 * If truncating down to a partial page, then 648 * if that page is already allocated, hold it 649 * in memory until the truncation is over, so 650 * truncate_partial_page cannnot miss it were 651 * it assigned to swap. 652 */ 653 if (attr->ia_size & (PAGE_CACHE_SIZE-1)) { 654 (void) shmem_getpage(inode, 655 attr->ia_size>>PAGE_CACHE_SHIFT, 656 &page, SGP_READ, NULL); 657 } 658 /* 659 * Reset SHMEM_PAGEIN flag so that shmem_truncate can 660 * detect if any pages might have been added to cache 661 * after truncate_inode_pages. But we needn't bother 662 * if it's being fully truncated to zero-length: the 663 * nrpages check is efficient enough in that case. 664 */ 665 if (attr->ia_size) { 666 struct shmem_inode_info *info = SHMEM_I(inode); 667 spin_lock(&info->lock); 668 info->flags &= ~SHMEM_PAGEIN; 669 spin_unlock(&info->lock); 670 } 671 } 672 } 673 674 error = inode_change_ok(inode, attr); 675 if (!error) 676 error = inode_setattr(inode, attr); 677#ifdef CONFIG_TMPFS_POSIX_ACL 678 if (!error && (attr->ia_valid & ATTR_MODE)) 679 error = generic_acl_chmod(inode, &shmem_acl_ops); 680#endif 681 if (page) 682 page_cache_release(page); 683 return error; 684} 685 686static void shmem_delete_inode(struct inode *inode) 687{ 688 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 689 struct shmem_inode_info *info = SHMEM_I(inode); 690 691 if (inode->i_op->truncate == shmem_truncate) { 692 truncate_inode_pages(inode->i_mapping, 0); 693 shmem_unacct_size(info->flags, inode->i_size); 694 inode->i_size = 0; 695 shmem_truncate(inode); 696 if (!list_empty(&info->swaplist)) { 697 spin_lock(&shmem_swaplist_lock); 698 list_del_init(&info->swaplist); 699 spin_unlock(&shmem_swaplist_lock); 700 } 701 } 702 BUG_ON(inode->i_blocks); 703 if (sbinfo->max_inodes) { 704 spin_lock(&sbinfo->stat_lock); 705 sbinfo->free_inodes++; 706 spin_unlock(&sbinfo->stat_lock); 707 } 708 clear_inode(inode); 709} 710 711static inline int shmem_find_swp(swp_entry_t entry, swp_entry_t *dir, swp_entry_t *edir) 712{ 713 swp_entry_t *ptr; 714 715 for (ptr = dir; ptr < edir; ptr++) { 716 if (ptr->val == entry.val) 717 return ptr - dir; 718 } 719 return -1; 720} 721 722static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, struct page *page) 723{ 724 struct inode *inode; 725 unsigned long idx; 726 unsigned long size; 727 unsigned long limit; 728 unsigned long stage; 729 struct page **dir; 730 struct page *subdir; 731 swp_entry_t *ptr; 732 int offset; 733 734 idx = 0; 735 ptr = info->i_direct; 736 spin_lock(&info->lock); 737 limit = info->next_index; 738 size = limit; 739 if (size > SHMEM_NR_DIRECT) 740 size = SHMEM_NR_DIRECT; 741 offset = shmem_find_swp(entry, ptr, ptr+size); 742 if (offset >= 0) { 743 shmem_swp_balance_unmap(); 744 goto found; 745 } 746 if (!info->i_indirect) 747 goto lost2; 748 749 dir = shmem_dir_map(info->i_indirect); 750 stage = SHMEM_NR_DIRECT + ENTRIES_PER_PAGEPAGE/2; 751 752 for (idx = SHMEM_NR_DIRECT; idx < limit; idx += ENTRIES_PER_PAGE, dir++) { 753 if (unlikely(idx == stage)) { 754 shmem_dir_unmap(dir-1); 755 dir = shmem_dir_map(info->i_indirect) + 756 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE; 757 while (!*dir) { 758 dir++; 759 idx += ENTRIES_PER_PAGEPAGE; 760 if (idx >= limit) 761 goto lost1; 762 } 763 stage = idx + ENTRIES_PER_PAGEPAGE; 764 subdir = *dir; 765 shmem_dir_unmap(dir); 766 dir = shmem_dir_map(subdir); 767 } 768 subdir = *dir; 769 if (subdir && page_private(subdir)) { 770 ptr = shmem_swp_map(subdir); 771 size = limit - idx; 772 if (size > ENTRIES_PER_PAGE) 773 size = ENTRIES_PER_PAGE; 774 offset = shmem_find_swp(entry, ptr, ptr+size); 775 if (offset >= 0) { 776 shmem_dir_unmap(dir); 777 goto found; 778 } 779 shmem_swp_unmap(ptr); 780 } 781 } 782lost1: 783 shmem_dir_unmap(dir-1); 784lost2: 785 spin_unlock(&info->lock); 786 return 0; 787found: 788 idx += offset; 789 inode = &info->vfs_inode; 790 if (move_from_swap_cache(page, idx, inode->i_mapping) == 0) { 791 info->flags |= SHMEM_PAGEIN; 792 shmem_swp_set(info, ptr + offset, 0); 793 } 794 shmem_swp_unmap(ptr); 795 spin_unlock(&info->lock); 796 /* 797 * Decrement swap count even when the entry is left behind: 798 * try_to_unuse will skip over mms, then reincrement count. 799 */ 800 swap_free(entry); 801 return 1; 802} 803 804/* 805 * shmem_unuse() search for an eventually swapped out shmem page. 806 */ 807int shmem_unuse(swp_entry_t entry, struct page *page) 808{ 809 struct list_head *p, *next; 810 struct shmem_inode_info *info; 811 int found = 0; 812 813 spin_lock(&shmem_swaplist_lock); 814 list_for_each_safe(p, next, &shmem_swaplist) { 815 info = list_entry(p, struct shmem_inode_info, swaplist); 816 if (!info->swapped) 817 list_del_init(&info->swaplist); 818 else if (shmem_unuse_inode(info, entry, page)) { 819 /* move head to start search for next from here */ 820 list_move_tail(&shmem_swaplist, &info->swaplist); 821 found = 1; 822 break; 823 } 824 } 825 spin_unlock(&shmem_swaplist_lock); 826 return found; 827} 828 829/* 830 * Move the page from the page cache to the swap cache. 831 */ 832static int shmem_writepage(struct page *page, struct writeback_control *wbc) 833{ 834 struct shmem_inode_info *info; 835 swp_entry_t *entry, swap; 836 struct address_space *mapping; 837 unsigned long index; 838 struct inode *inode; 839 840 BUG_ON(!PageLocked(page)); 841 BUG_ON(page_mapped(page)); 842 843 mapping = page->mapping; 844 index = page->index; 845 inode = mapping->host; 846 info = SHMEM_I(inode); 847 if (info->flags & VM_LOCKED) 848 goto redirty; 849 swap = get_swap_page(); 850 if (!swap.val) 851 goto redirty; 852 853 spin_lock(&info->lock); 854 shmem_recalc_inode(inode); 855 if (index >= info->next_index) { 856 BUG_ON(!(info->flags & SHMEM_TRUNCATE)); 857 goto unlock; 858 } 859 entry = shmem_swp_entry(info, index, NULL); 860 BUG_ON(!entry); 861 BUG_ON(entry->val); 862 863 if (move_to_swap_cache(page, swap) == 0) { 864 shmem_swp_set(info, entry, swap.val); 865 shmem_swp_unmap(entry); 866 spin_unlock(&info->lock); 867 if (list_empty(&info->swaplist)) { 868 spin_lock(&shmem_swaplist_lock); 869 /* move instead of add in case we're racing */ 870 list_move_tail(&info->swaplist, &shmem_swaplist); 871 spin_unlock(&shmem_swaplist_lock); 872 } 873 unlock_page(page); 874 return 0; 875 } 876 877 shmem_swp_unmap(entry); 878unlock: 879 spin_unlock(&info->lock); 880 swap_free(swap); 881redirty: 882 set_page_dirty(page); 883 return AOP_WRITEPAGE_ACTIVATE; /* Return with the page locked */ 884} 885 886#ifdef CONFIG_NUMA 887static inline int shmem_parse_mpol(char *value, int *policy, nodemask_t *policy_nodes) 888{ 889 char *nodelist = strchr(value, ':'); 890 int err = 1; 891 892 if (nodelist) { 893 /* NUL-terminate policy string */ 894 *nodelist++ = '\0'; 895 if (nodelist_parse(nodelist, *policy_nodes)) 896 goto out; 897 } 898 if (!strcmp(value, "default")) { 899 *policy = MPOL_DEFAULT; 900 /* Don't allow a nodelist */ 901 if (!nodelist) 902 err = 0; 903 } else if (!strcmp(value, "prefer")) { 904 *policy = MPOL_PREFERRED; 905 /* Insist on a nodelist of one node only */ 906 if (nodelist) { 907 char *rest = nodelist; 908 while (isdigit(*rest)) 909 rest++; 910 if (!*rest) 911 err = 0; 912 } 913 } else if (!strcmp(value, "bind")) { 914 *policy = MPOL_BIND; 915 /* Insist on a nodelist */ 916 if (nodelist) 917 err = 0; 918 } else if (!strcmp(value, "interleave")) { 919 *policy = MPOL_INTERLEAVE; 920 /* Default to nodes online if no nodelist */ 921 if (!nodelist) 922 *policy_nodes = node_online_map; 923 err = 0; 924 } 925out: 926 /* Restore string for error message */ 927 if (nodelist) 928 *--nodelist = ':'; 929 return err; 930} 931 932static struct page *shmem_swapin_async(struct shared_policy *p, 933 swp_entry_t entry, unsigned long idx) 934{ 935 struct page *page; 936 struct vm_area_struct pvma; 937 938 /* Create a pseudo vma that just contains the policy */ 939 memset(&pvma, 0, sizeof(struct vm_area_struct)); 940 pvma.vm_end = PAGE_SIZE; 941 pvma.vm_pgoff = idx; 942 pvma.vm_policy = mpol_shared_policy_lookup(p, idx); 943 page = read_swap_cache_async(entry, &pvma, 0); 944 mpol_free(pvma.vm_policy); 945 return page; 946} 947 948struct page *shmem_swapin(struct shmem_inode_info *info, swp_entry_t entry, 949 unsigned long idx) 950{ 951 struct shared_policy *p = &info->policy; 952 int i, num; 953 struct page *page; 954 unsigned long offset; 955 956 num = valid_swaphandles(entry, &offset); 957 for (i = 0; i < num; offset++, i++) { 958 page = shmem_swapin_async(p, 959 swp_entry(swp_type(entry), offset), idx); 960 if (!page) 961 break; 962 page_cache_release(page); 963 } 964 lru_add_drain(); /* Push any new pages onto the LRU now */ 965 return shmem_swapin_async(p, entry, idx); 966} 967 968static struct page * 969shmem_alloc_page(gfp_t gfp, struct shmem_inode_info *info, 970 unsigned long idx) 971{ 972 struct vm_area_struct pvma; 973 struct page *page; 974 975 memset(&pvma, 0, sizeof(struct vm_area_struct)); 976 pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx); 977 pvma.vm_pgoff = idx; 978 pvma.vm_end = PAGE_SIZE; 979 page = alloc_page_vma(gfp | __GFP_ZERO, &pvma, 0); 980 mpol_free(pvma.vm_policy); 981 return page; 982} 983#else 984static inline int shmem_parse_mpol(char *value, int *policy, nodemask_t *policy_nodes) 985{ 986 return 1; 987} 988 989static inline struct page * 990shmem_swapin(struct shmem_inode_info *info,swp_entry_t entry,unsigned long idx) 991{ 992 swapin_readahead(entry, 0, NULL); 993 return read_swap_cache_async(entry, NULL, 0); 994} 995 996static inline struct page * 997shmem_alloc_page(gfp_t gfp,struct shmem_inode_info *info, unsigned long idx) 998{ 999 return alloc_page(gfp | __GFP_ZERO); 1000} 1001#endif 1002 1003/* 1004 * shmem_getpage - either get the page from swap or allocate a new one 1005 * 1006 * If we allocate a new one we do not mark it dirty. That's up to the 1007 * vm. If we swap it in we mark it dirty since we also free the swap 1008 * entry since a page cannot live in both the swap and page cache 1009 */ 1010static int shmem_getpage(struct inode *inode, unsigned long idx, 1011 struct page **pagep, enum sgp_type sgp, int *type) 1012{ 1013 struct address_space *mapping = inode->i_mapping; 1014 struct shmem_inode_info *info = SHMEM_I(inode); 1015 struct shmem_sb_info *sbinfo; 1016 struct page *filepage = *pagep; 1017 struct page *swappage; 1018 swp_entry_t *entry; 1019 swp_entry_t swap; 1020 int error; 1021 1022 if (idx >= SHMEM_MAX_INDEX) 1023 return -EFBIG; 1024 /* 1025 * Normally, filepage is NULL on entry, and either found 1026 * uptodate immediately, or allocated and zeroed, or read 1027 * in under swappage, which is then assigned to filepage. 1028 * But shmem_prepare_write passes in a locked filepage, 1029 * which may be found not uptodate by other callers too, 1030 * and may need to be copied from the swappage read in. 1031 */ 1032repeat: 1033 if (!filepage) 1034 filepage = find_lock_page(mapping, idx); 1035 if (filepage && PageUptodate(filepage)) 1036 goto done; 1037 error = 0; 1038 if (sgp == SGP_QUICK) 1039 goto failed; 1040 1041 spin_lock(&info->lock); 1042 shmem_recalc_inode(inode); 1043 entry = shmem_swp_alloc(info, idx, sgp); 1044 if (IS_ERR(entry)) { 1045 spin_unlock(&info->lock); 1046 error = PTR_ERR(entry); 1047 goto failed; 1048 } 1049 swap = *entry; 1050 1051 if (swap.val) { 1052 /* Look it up and read it in.. */ 1053 swappage = lookup_swap_cache(swap); 1054 if (!swappage) { 1055 shmem_swp_unmap(entry); 1056 /* here we actually do the io */ 1057 if (type && *type == VM_FAULT_MINOR) { 1058 __count_vm_event(PGMAJFAULT); 1059 *type = VM_FAULT_MAJOR; 1060 } 1061 spin_unlock(&info->lock); 1062 swappage = shmem_swapin(info, swap, idx); 1063 if (!swappage) { 1064 spin_lock(&info->lock); 1065 entry = shmem_swp_alloc(info, idx, sgp); 1066 if (IS_ERR(entry)) 1067 error = PTR_ERR(entry); 1068 else { 1069 if (entry->val == swap.val) 1070 error = -ENOMEM; 1071 shmem_swp_unmap(entry); 1072 } 1073 spin_unlock(&info->lock); 1074 if (error) 1075 goto failed; 1076 goto repeat; 1077 } 1078 wait_on_page_locked(swappage); 1079 page_cache_release(swappage); 1080 goto repeat; 1081 } 1082 1083 /* We have to do this with page locked to prevent races */ 1084 if (TestSetPageLocked(swappage)) { 1085 shmem_swp_unmap(entry); 1086 spin_unlock(&info->lock); 1087 wait_on_page_locked(swappage); 1088 page_cache_release(swappage); 1089 goto repeat; 1090 } 1091 if (PageWriteback(swappage)) { 1092 shmem_swp_unmap(entry); 1093 spin_unlock(&info->lock); 1094 wait_on_page_writeback(swappage); 1095 unlock_page(swappage); 1096 page_cache_release(swappage); 1097 goto repeat; 1098 } 1099 if (!PageUptodate(swappage)) { 1100 shmem_swp_unmap(entry); 1101 spin_unlock(&info->lock); 1102 unlock_page(swappage); 1103 page_cache_release(swappage); 1104 error = -EIO; 1105 goto failed; 1106 } 1107 1108 if (filepage) { 1109 shmem_swp_set(info, entry, 0); 1110 shmem_swp_unmap(entry); 1111 delete_from_swap_cache(swappage); 1112 spin_unlock(&info->lock); 1113 copy_highpage(filepage, swappage); 1114 unlock_page(swappage); 1115 page_cache_release(swappage); 1116 flush_dcache_page(filepage); 1117 SetPageUptodate(filepage); 1118 set_page_dirty(filepage); 1119 swap_free(swap); 1120 } else if (!(error = move_from_swap_cache( 1121 swappage, idx, mapping))) { 1122 info->flags |= SHMEM_PAGEIN; 1123 shmem_swp_set(info, entry, 0); 1124 shmem_swp_unmap(entry); 1125 spin_unlock(&info->lock); 1126 filepage = swappage; 1127 swap_free(swap); 1128 } else { 1129 shmem_swp_unmap(entry); 1130 spin_unlock(&info->lock); 1131 unlock_page(swappage); 1132 page_cache_release(swappage); 1133 if (error == -ENOMEM) { 1134 /* let kswapd refresh zone for GFP_ATOMICs */ 1135 congestion_wait(WRITE, HZ/50); 1136 } 1137 goto repeat; 1138 } 1139 } else if (sgp == SGP_READ && !filepage) { 1140 shmem_swp_unmap(entry); 1141 filepage = find_get_page(mapping, idx); 1142 if (filepage && 1143 (!PageUptodate(filepage) || TestSetPageLocked(filepage))) { 1144 spin_unlock(&info->lock); 1145 wait_on_page_locked(filepage); 1146 page_cache_release(filepage); 1147 filepage = NULL; 1148 goto repeat; 1149 } 1150 spin_unlock(&info->lock); 1151 } else { 1152 shmem_swp_unmap(entry); 1153 sbinfo = SHMEM_SB(inode->i_sb); 1154 if (sbinfo->max_blocks) { 1155 spin_lock(&sbinfo->stat_lock); 1156 if (sbinfo->free_blocks == 0 || 1157 shmem_acct_block(info->flags)) { 1158 spin_unlock(&sbinfo->stat_lock); 1159 spin_unlock(&info->lock); 1160 error = -ENOSPC; 1161 goto failed; 1162 } 1163 sbinfo->free_blocks--; 1164 inode->i_blocks += BLOCKS_PER_PAGE; 1165 spin_unlock(&sbinfo->stat_lock); 1166 } else if (shmem_acct_block(info->flags)) { 1167 spin_unlock(&info->lock); 1168 error = -ENOSPC; 1169 goto failed; 1170 } 1171 1172 if (!filepage) { 1173 spin_unlock(&info->lock); 1174 filepage = shmem_alloc_page(mapping_gfp_mask(mapping), 1175 info, 1176 idx); 1177 if (!filepage) { 1178 shmem_unacct_blocks(info->flags, 1); 1179 shmem_free_blocks(inode, 1); 1180 error = -ENOMEM; 1181 goto failed; 1182 } 1183 1184 spin_lock(&info->lock); 1185 entry = shmem_swp_alloc(info, idx, sgp); 1186 if (IS_ERR(entry)) 1187 error = PTR_ERR(entry); 1188 else { 1189 swap = *entry; 1190 shmem_swp_unmap(entry); 1191 } 1192 if (error || swap.val || 0 != add_to_page_cache_lru( 1193 filepage, mapping, idx, GFP_ATOMIC)) { 1194 spin_unlock(&info->lock); 1195 page_cache_release(filepage); 1196 shmem_unacct_blocks(info->flags, 1); 1197 shmem_free_blocks(inode, 1); 1198 filepage = NULL; 1199 if (error) 1200 goto failed; 1201 goto repeat; 1202 } 1203 info->flags |= SHMEM_PAGEIN; 1204 } 1205 1206 info->alloced++; 1207 spin_unlock(&info->lock); 1208 flush_dcache_page(filepage); 1209 SetPageUptodate(filepage); 1210 } 1211done: 1212 if (*pagep != filepage) { 1213 unlock_page(filepage); 1214 *pagep = filepage; 1215 } 1216 return 0; 1217 1218failed: 1219 if (*pagep != filepage) { 1220 unlock_page(filepage); 1221 page_cache_release(filepage); 1222 } 1223 return error; 1224} 1225 1226struct page *shmem_nopage(struct vm_area_struct *vma, unsigned long address, int *type) 1227{ 1228 struct inode *inode = vma->vm_file->f_dentry->d_inode; 1229 struct page *page = NULL; 1230 unsigned long idx; 1231 int error; 1232 1233 idx = (address - vma->vm_start) >> PAGE_SHIFT; 1234 idx += vma->vm_pgoff; 1235 idx >>= PAGE_CACHE_SHIFT - PAGE_SHIFT; 1236 if (((loff_t) idx << PAGE_CACHE_SHIFT) >= i_size_read(inode)) 1237 return NOPAGE_SIGBUS; 1238 1239 error = shmem_getpage(inode, idx, &page, SGP_CACHE, type); 1240 if (error) 1241 return (error == -ENOMEM)? NOPAGE_OOM: NOPAGE_SIGBUS; 1242 1243 mark_page_accessed(page); 1244 return page; 1245} 1246 1247static int shmem_populate(struct vm_area_struct *vma, 1248 unsigned long addr, unsigned long len, 1249 pgprot_t prot, unsigned long pgoff, int nonblock) 1250{ 1251 struct inode *inode = vma->vm_file->f_dentry->d_inode; 1252 struct mm_struct *mm = vma->vm_mm; 1253 enum sgp_type sgp = nonblock? SGP_QUICK: SGP_CACHE; 1254 unsigned long size; 1255 1256 size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT; 1257 if (pgoff >= size || pgoff + (len >> PAGE_SHIFT) > size) 1258 return -EINVAL; 1259 1260 while ((long) len > 0) { 1261 struct page *page = NULL; 1262 int err; 1263 /* 1264 * Will need changing if PAGE_CACHE_SIZE != PAGE_SIZE 1265 */ 1266 err = shmem_getpage(inode, pgoff, &page, sgp, NULL); 1267 if (err) 1268 return err; 1269 /* Page may still be null, but only if nonblock was set. */ 1270 if (page) { 1271 mark_page_accessed(page); 1272 err = install_page(mm, vma, addr, page, prot); 1273 if (err) { 1274 page_cache_release(page); 1275 return err; 1276 } 1277 } else if (vma->vm_flags & VM_NONLINEAR) { 1278 /* No page was found just because we can't read it in 1279 * now (being here implies nonblock != 0), but the page 1280 * may exist, so set the PTE to fault it in later. */ 1281 err = install_file_pte(mm, vma, addr, pgoff, prot); 1282 if (err) 1283 return err; 1284 } 1285 1286 len -= PAGE_SIZE; 1287 addr += PAGE_SIZE; 1288 pgoff++; 1289 } 1290 return 0; 1291} 1292 1293#ifdef CONFIG_NUMA 1294int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *new) 1295{ 1296 struct inode *i = vma->vm_file->f_dentry->d_inode; 1297 return mpol_set_shared_policy(&SHMEM_I(i)->policy, vma, new); 1298} 1299 1300struct mempolicy * 1301shmem_get_policy(struct vm_area_struct *vma, unsigned long addr) 1302{ 1303 struct inode *i = vma->vm_file->f_dentry->d_inode; 1304 unsigned long idx; 1305 1306 idx = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; 1307 return mpol_shared_policy_lookup(&SHMEM_I(i)->policy, idx); 1308} 1309#endif 1310 1311int shmem_lock(struct file *file, int lock, struct user_struct *user) 1312{ 1313 struct inode *inode = file->f_dentry->d_inode; 1314 struct shmem_inode_info *info = SHMEM_I(inode); 1315 int retval = -ENOMEM; 1316 1317 spin_lock(&info->lock); 1318 if (lock && !(info->flags & VM_LOCKED)) { 1319 if (!user_shm_lock(inode->i_size, user)) 1320 goto out_nomem; 1321 info->flags |= VM_LOCKED; 1322 } 1323 if (!lock && (info->flags & VM_LOCKED) && user) { 1324 user_shm_unlock(inode->i_size, user); 1325 info->flags &= ~VM_LOCKED; 1326 } 1327 retval = 0; 1328out_nomem: 1329 spin_unlock(&info->lock); 1330 return retval; 1331} 1332 1333int shmem_mmap(struct file *file, struct vm_area_struct *vma) 1334{ 1335 file_accessed(file); 1336 vma->vm_ops = &shmem_vm_ops; 1337 return 0; 1338} 1339 1340static struct inode * 1341shmem_get_inode(struct super_block *sb, int mode, dev_t dev) 1342{ 1343 struct inode *inode; 1344 struct shmem_inode_info *info; 1345 struct shmem_sb_info *sbinfo = SHMEM_SB(sb); 1346 1347 if (sbinfo->max_inodes) { 1348 spin_lock(&sbinfo->stat_lock); 1349 if (!sbinfo->free_inodes) { 1350 spin_unlock(&sbinfo->stat_lock); 1351 return NULL; 1352 } 1353 sbinfo->free_inodes--; 1354 spin_unlock(&sbinfo->stat_lock); 1355 } 1356 1357 inode = new_inode(sb); 1358 if (inode) { 1359 inode->i_mode = mode; 1360 inode->i_uid = current->fsuid; 1361 inode->i_gid = current->fsgid; 1362 inode->i_blocks = 0; 1363 inode->i_mapping->a_ops = &shmem_aops; 1364 inode->i_mapping->backing_dev_info = &shmem_backing_dev_info; 1365 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; 1366 inode->i_generation = get_seconds(); 1367 info = SHMEM_I(inode); 1368 memset(info, 0, (char *)inode - (char *)info); 1369 spin_lock_init(&info->lock); 1370 INIT_LIST_HEAD(&info->swaplist); 1371 1372 switch (mode & S_IFMT) { 1373 default: 1374 inode->i_op = &shmem_special_inode_operations; 1375 init_special_inode(inode, mode, dev); 1376 break; 1377 case S_IFREG: 1378 inode->i_op = &shmem_inode_operations; 1379 inode->i_fop = &shmem_file_operations; 1380 mpol_shared_policy_init(&info->policy, sbinfo->policy, 1381 &sbinfo->policy_nodes); 1382 break; 1383 case S_IFDIR: 1384 inc_nlink(inode); 1385 /* Some things misbehave if size == 0 on a directory */ 1386 inode->i_size = 2 * BOGO_DIRENT_SIZE; 1387 inode->i_op = &shmem_dir_inode_operations; 1388 inode->i_fop = &simple_dir_operations; 1389 break; 1390 case S_IFLNK: 1391 /* 1392 * Must not load anything in the rbtree, 1393 * mpol_free_shared_policy will not be called. 1394 */ 1395 mpol_shared_policy_init(&info->policy, MPOL_DEFAULT, 1396 NULL); 1397 break; 1398 } 1399 } else if (sbinfo->max_inodes) { 1400 spin_lock(&sbinfo->stat_lock); 1401 sbinfo->free_inodes++; 1402 spin_unlock(&sbinfo->stat_lock); 1403 } 1404 return inode; 1405} 1406 1407#ifdef CONFIG_TMPFS 1408static struct inode_operations shmem_symlink_inode_operations; 1409static struct inode_operations shmem_symlink_inline_operations; 1410 1411/* 1412 * Normally tmpfs makes no use of shmem_prepare_write, but it 1413 * lets a tmpfs file be used read-write below the loop driver. 1414 */ 1415static int 1416shmem_prepare_write(struct file *file, struct page *page, unsigned offset, unsigned to) 1417{ 1418 struct inode *inode = page->mapping->host; 1419 return shmem_getpage(inode, page->index, &page, SGP_WRITE, NULL); 1420} 1421 1422static ssize_t 1423shmem_file_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos) 1424{ 1425 struct inode *inode = file->f_dentry->d_inode; 1426 loff_t pos; 1427 unsigned long written; 1428 ssize_t err; 1429 1430 if ((ssize_t) count < 0) 1431 return -EINVAL; 1432 1433 if (!access_ok(VERIFY_READ, buf, count)) 1434 return -EFAULT; 1435 1436 mutex_lock(&inode->i_mutex); 1437 1438 pos = *ppos; 1439 written = 0; 1440 1441 err = generic_write_checks(file, &pos, &count, 0); 1442 if (err || !count) 1443 goto out; 1444 1445 err = remove_suid(file->f_dentry); 1446 if (err) 1447 goto out; 1448 1449 inode->i_ctime = inode->i_mtime = CURRENT_TIME; 1450 1451 do { 1452 struct page *page = NULL; 1453 unsigned long bytes, index, offset; 1454 char *kaddr; 1455 int left; 1456 1457 offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */ 1458 index = pos >> PAGE_CACHE_SHIFT; 1459 bytes = PAGE_CACHE_SIZE - offset; 1460 if (bytes > count) 1461 bytes = count; 1462 1463 /* 1464 * We don't hold page lock across copy from user - 1465 * what would it guard against? - so no deadlock here. 1466 * But it still may be a good idea to prefault below. 1467 */ 1468 1469 err = shmem_getpage(inode, index, &page, SGP_WRITE, NULL); 1470 if (err) 1471 break; 1472 1473 left = bytes; 1474 if (PageHighMem(page)) { 1475 volatile unsigned char dummy; 1476 __get_user(dummy, buf); 1477 __get_user(dummy, buf + bytes - 1); 1478 1479 kaddr = kmap_atomic(page, KM_USER0); 1480 left = __copy_from_user_inatomic(kaddr + offset, 1481 buf, bytes); 1482 kunmap_atomic(kaddr, KM_USER0); 1483 } 1484 if (left) { 1485 kaddr = kmap(page); 1486 left = __copy_from_user(kaddr + offset, buf, bytes); 1487 kunmap(page); 1488 } 1489 1490 written += bytes; 1491 count -= bytes; 1492 pos += bytes; 1493 buf += bytes; 1494 if (pos > inode->i_size) 1495 i_size_write(inode, pos); 1496 1497 flush_dcache_page(page); 1498 set_page_dirty(page); 1499 mark_page_accessed(page); 1500 page_cache_release(page); 1501 1502 if (left) { 1503 pos -= left; 1504 written -= left; 1505 err = -EFAULT; 1506 break; 1507 } 1508 1509 /* 1510 * Our dirty pages are not counted in nr_dirty, 1511 * and we do not attempt to balance dirty pages. 1512 */ 1513 1514 cond_resched(); 1515 } while (count); 1516 1517 *ppos = pos; 1518 if (written) 1519 err = written; 1520out: 1521 mutex_unlock(&inode->i_mutex); 1522 return err; 1523} 1524 1525static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor) 1526{ 1527 struct inode *inode = filp->f_dentry->d_inode; 1528 struct address_space *mapping = inode->i_mapping; 1529 unsigned long index, offset; 1530 1531 index = *ppos >> PAGE_CACHE_SHIFT; 1532 offset = *ppos & ~PAGE_CACHE_MASK; 1533 1534 for (;;) { 1535 struct page *page = NULL; 1536 unsigned long end_index, nr, ret; 1537 loff_t i_size = i_size_read(inode); 1538 1539 end_index = i_size >> PAGE_CACHE_SHIFT; 1540 if (index > end_index) 1541 break; 1542 if (index == end_index) { 1543 nr = i_size & ~PAGE_CACHE_MASK; 1544 if (nr <= offset) 1545 break; 1546 } 1547 1548 desc->error = shmem_getpage(inode, index, &page, SGP_READ, NULL); 1549 if (desc->error) { 1550 if (desc->error == -EINVAL) 1551 desc->error = 0; 1552 break; 1553 } 1554 1555 /* 1556 * We must evaluate after, since reads (unlike writes) 1557 * are called without i_mutex protection against truncate 1558 */ 1559 nr = PAGE_CACHE_SIZE; 1560 i_size = i_size_read(inode); 1561 end_index = i_size >> PAGE_CACHE_SHIFT; 1562 if (index == end_index) { 1563 nr = i_size & ~PAGE_CACHE_MASK; 1564 if (nr <= offset) { 1565 if (page) 1566 page_cache_release(page); 1567 break; 1568 } 1569 } 1570 nr -= offset; 1571 1572 if (page) { 1573 /* 1574 * If users can be writing to this page using arbitrary 1575 * virtual addresses, take care about potential aliasing 1576 * before reading the page on the kernel side. 1577 */ 1578 if (mapping_writably_mapped(mapping)) 1579 flush_dcache_page(page); 1580 /* 1581 * Mark the page accessed if we read the beginning. 1582 */ 1583 if (!offset) 1584 mark_page_accessed(page); 1585 } else { 1586 page = ZERO_PAGE(0); 1587 page_cache_get(page); 1588 } 1589 1590 /* 1591 * Ok, we have the page, and it's up-to-date, so 1592 * now we can copy it to user space... 1593 * 1594 * The actor routine returns how many bytes were actually used.. 1595 * NOTE! This may not be the same as how much of a user buffer 1596 * we filled up (we may be padding etc), so we can only update 1597 * "pos" here (the actor routine has to update the user buffer 1598 * pointers and the remaining count). 1599 */ 1600 ret = actor(desc, page, offset, nr); 1601 offset += ret; 1602 index += offset >> PAGE_CACHE_SHIFT; 1603 offset &= ~PAGE_CACHE_MASK; 1604 1605 page_cache_release(page); 1606 if (ret != nr || !desc->count) 1607 break; 1608 1609 cond_resched(); 1610 } 1611 1612 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset; 1613 file_accessed(filp); 1614} 1615 1616static ssize_t shmem_file_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos) 1617{ 1618 read_descriptor_t desc; 1619 1620 if ((ssize_t) count < 0) 1621 return -EINVAL; 1622 if (!access_ok(VERIFY_WRITE, buf, count)) 1623 return -EFAULT; 1624 if (!count) 1625 return 0; 1626 1627 desc.written = 0; 1628 desc.count = count; 1629 desc.arg.buf = buf; 1630 desc.error = 0; 1631 1632 do_shmem_file_read(filp, ppos, &desc, file_read_actor); 1633 if (desc.written) 1634 return desc.written; 1635 return desc.error; 1636} 1637 1638static ssize_t shmem_file_sendfile(struct file *in_file, loff_t *ppos, 1639 size_t count, read_actor_t actor, void *target) 1640{ 1641 read_descriptor_t desc; 1642 1643 if (!count) 1644 return 0; 1645 1646 desc.written = 0; 1647 desc.count = count; 1648 desc.arg.data = target; 1649 desc.error = 0; 1650 1651 do_shmem_file_read(in_file, ppos, &desc, actor); 1652 if (desc.written) 1653 return desc.written; 1654 return desc.error; 1655} 1656 1657static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf) 1658{ 1659 struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb); 1660 1661 buf->f_type = TMPFS_MAGIC; 1662 buf->f_bsize = PAGE_CACHE_SIZE; 1663 buf->f_namelen = NAME_MAX; 1664 spin_lock(&sbinfo->stat_lock); 1665 if (sbinfo->max_blocks) { 1666 buf->f_blocks = sbinfo->max_blocks; 1667 buf->f_bavail = buf->f_bfree = sbinfo->free_blocks; 1668 } 1669 if (sbinfo->max_inodes) { 1670 buf->f_files = sbinfo->max_inodes; 1671 buf->f_ffree = sbinfo->free_inodes; 1672 } 1673 /* else leave those fields 0 like simple_statfs */ 1674 spin_unlock(&sbinfo->stat_lock); 1675 return 0; 1676} 1677 1678/* 1679 * File creation. Allocate an inode, and we're done.. 1680 */ 1681static int 1682shmem_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) 1683{ 1684 struct inode *inode = shmem_get_inode(dir->i_sb, mode, dev); 1685 int error = -ENOSPC; 1686 1687 if (inode) { 1688 error = security_inode_init_security(inode, dir, NULL, NULL, 1689 NULL); 1690 if (error) { 1691 if (error != -EOPNOTSUPP) { 1692 iput(inode); 1693 return error; 1694 } 1695 } 1696 error = shmem_acl_init(inode, dir); 1697 if (error) { 1698 iput(inode); 1699 return error; 1700 } 1701 if (dir->i_mode & S_ISGID) { 1702 inode->i_gid = dir->i_gid; 1703 if (S_ISDIR(mode)) 1704 inode->i_mode |= S_ISGID; 1705 } 1706 dir->i_size += BOGO_DIRENT_SIZE; 1707 dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1708 d_instantiate(dentry, inode); 1709 dget(dentry); /* Extra count - pin the dentry in core */ 1710 } 1711 return error; 1712} 1713 1714static int shmem_mkdir(struct inode *dir, struct dentry *dentry, int mode) 1715{ 1716 int error; 1717 1718 if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0))) 1719 return error; 1720 inc_nlink(dir); 1721 return 0; 1722} 1723 1724static int shmem_create(struct inode *dir, struct dentry *dentry, int mode, 1725 struct nameidata *nd) 1726{ 1727 return shmem_mknod(dir, dentry, mode | S_IFREG, 0); 1728} 1729 1730/* 1731 * Link a file.. 1732 */ 1733static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry) 1734{ 1735 struct inode *inode = old_dentry->d_inode; 1736 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 1737 1738 /* 1739 * No ordinary (disk based) filesystem counts links as inodes; 1740 * but each new link needs a new dentry, pinning lowmem, and 1741 * tmpfs dentries cannot be pruned until they are unlinked. 1742 */ 1743 if (sbinfo->max_inodes) { 1744 spin_lock(&sbinfo->stat_lock); 1745 if (!sbinfo->free_inodes) { 1746 spin_unlock(&sbinfo->stat_lock); 1747 return -ENOSPC; 1748 } 1749 sbinfo->free_inodes--; 1750 spin_unlock(&sbinfo->stat_lock); 1751 } 1752 1753 dir->i_size += BOGO_DIRENT_SIZE; 1754 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1755 inc_nlink(inode); 1756 atomic_inc(&inode->i_count); /* New dentry reference */ 1757 dget(dentry); /* Extra pinning count for the created dentry */ 1758 d_instantiate(dentry, inode); 1759 return 0; 1760} 1761 1762static int shmem_unlink(struct inode *dir, struct dentry *dentry) 1763{ 1764 struct inode *inode = dentry->d_inode; 1765 1766 if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode)) { 1767 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 1768 if (sbinfo->max_inodes) { 1769 spin_lock(&sbinfo->stat_lock); 1770 sbinfo->free_inodes++; 1771 spin_unlock(&sbinfo->stat_lock); 1772 } 1773 } 1774 1775 dir->i_size -= BOGO_DIRENT_SIZE; 1776 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1777 drop_nlink(inode); 1778 dput(dentry); /* Undo the count from "create" - this does all the work */ 1779 return 0; 1780} 1781 1782static int shmem_rmdir(struct inode *dir, struct dentry *dentry) 1783{ 1784 if (!simple_empty(dentry)) 1785 return -ENOTEMPTY; 1786 1787 drop_nlink(dentry->d_inode); 1788 drop_nlink(dir); 1789 return shmem_unlink(dir, dentry); 1790} 1791 1792/* 1793 * The VFS layer already does all the dentry stuff for rename, 1794 * we just have to decrement the usage count for the target if 1795 * it exists so that the VFS layer correctly free's it when it 1796 * gets overwritten. 1797 */ 1798static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry) 1799{ 1800 struct inode *inode = old_dentry->d_inode; 1801 int they_are_dirs = S_ISDIR(inode->i_mode); 1802 1803 if (!simple_empty(new_dentry)) 1804 return -ENOTEMPTY; 1805 1806 if (new_dentry->d_inode) { 1807 (void) shmem_unlink(new_dir, new_dentry); 1808 if (they_are_dirs) 1809 drop_nlink(old_dir); 1810 } else if (they_are_dirs) { 1811 drop_nlink(old_dir); 1812 inc_nlink(new_dir); 1813 } 1814 1815 old_dir->i_size -= BOGO_DIRENT_SIZE; 1816 new_dir->i_size += BOGO_DIRENT_SIZE; 1817 old_dir->i_ctime = old_dir->i_mtime = 1818 new_dir->i_ctime = new_dir->i_mtime = 1819 inode->i_ctime = CURRENT_TIME; 1820 return 0; 1821} 1822 1823static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname) 1824{ 1825 int error; 1826 int len; 1827 struct inode *inode; 1828 struct page *page = NULL; 1829 char *kaddr; 1830 struct shmem_inode_info *info; 1831 1832 len = strlen(symname) + 1; 1833 if (len > PAGE_CACHE_SIZE) 1834 return -ENAMETOOLONG; 1835 1836 inode = shmem_get_inode(dir->i_sb, S_IFLNK|S_IRWXUGO, 0); 1837 if (!inode) 1838 return -ENOSPC; 1839 1840 error = security_inode_init_security(inode, dir, NULL, NULL, 1841 NULL); 1842 if (error) { 1843 if (error != -EOPNOTSUPP) { 1844 iput(inode); 1845 return error; 1846 } 1847 error = 0; 1848 } 1849 1850 info = SHMEM_I(inode); 1851 inode->i_size = len-1; 1852 if (len <= (char *)inode - (char *)info) { 1853 /* do it inline */ 1854 memcpy(info, symname, len); 1855 inode->i_op = &shmem_symlink_inline_operations; 1856 } else { 1857 error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL); 1858 if (error) { 1859 iput(inode); 1860 return error; 1861 } 1862 inode->i_op = &shmem_symlink_inode_operations; 1863 kaddr = kmap_atomic(page, KM_USER0); 1864 memcpy(kaddr, symname, len); 1865 kunmap_atomic(kaddr, KM_USER0); 1866 set_page_dirty(page); 1867 page_cache_release(page); 1868 } 1869 if (dir->i_mode & S_ISGID) 1870 inode->i_gid = dir->i_gid; 1871 dir->i_size += BOGO_DIRENT_SIZE; 1872 dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1873 d_instantiate(dentry, inode); 1874 dget(dentry); 1875 return 0; 1876} 1877 1878static void *shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd) 1879{ 1880 nd_set_link(nd, (char *)SHMEM_I(dentry->d_inode)); 1881 return NULL; 1882} 1883 1884static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd) 1885{ 1886 struct page *page = NULL; 1887 int res = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL); 1888 nd_set_link(nd, res ? ERR_PTR(res) : kmap(page)); 1889 return page; 1890} 1891 1892static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 1893{ 1894 if (!IS_ERR(nd_get_link(nd))) { 1895 struct page *page = cookie; 1896 kunmap(page); 1897 mark_page_accessed(page); 1898 page_cache_release(page); 1899 } 1900} 1901 1902static struct inode_operations shmem_symlink_inline_operations = { 1903 .readlink = generic_readlink, 1904 .follow_link = shmem_follow_link_inline, 1905}; 1906 1907static struct inode_operations shmem_symlink_inode_operations = { 1908 .truncate = shmem_truncate, 1909 .readlink = generic_readlink, 1910 .follow_link = shmem_follow_link, 1911 .put_link = shmem_put_link, 1912}; 1913 1914#ifdef CONFIG_TMPFS_POSIX_ACL 1915/** 1916 * Superblocks without xattr inode operations will get security.* xattr 1917 * support from the VFS "for free". As soon as we have any other xattrs 1918 * like ACLs, we also need to implement the security.* handlers at 1919 * filesystem level, though. 1920 */ 1921 1922static size_t shmem_xattr_security_list(struct inode *inode, char *list, 1923 size_t list_len, const char *name, 1924 size_t name_len) 1925{ 1926 return security_inode_listsecurity(inode, list, list_len); 1927} 1928 1929static int shmem_xattr_security_get(struct inode *inode, const char *name, 1930 void *buffer, size_t size) 1931{ 1932 if (strcmp(name, "") == 0) 1933 return -EINVAL; 1934 return security_inode_getsecurity(inode, name, buffer, size, 1935 -EOPNOTSUPP); 1936} 1937 1938static int shmem_xattr_security_set(struct inode *inode, const char *name, 1939 const void *value, size_t size, int flags) 1940{ 1941 if (strcmp(name, "") == 0) 1942 return -EINVAL; 1943 return security_inode_setsecurity(inode, name, value, size, flags); 1944} 1945 1946struct xattr_handler shmem_xattr_security_handler = { 1947 .prefix = XATTR_SECURITY_PREFIX, 1948 .list = shmem_xattr_security_list, 1949 .get = shmem_xattr_security_get, 1950 .set = shmem_xattr_security_set, 1951}; 1952 1953static struct xattr_handler *shmem_xattr_handlers[] = { 1954 &shmem_xattr_acl_access_handler, 1955 &shmem_xattr_acl_default_handler, 1956 &shmem_xattr_security_handler, 1957 NULL 1958}; 1959#endif 1960 1961static struct dentry *shmem_get_parent(struct dentry *child) 1962{ 1963 return ERR_PTR(-ESTALE); 1964} 1965 1966static int shmem_match(struct inode *ino, void *vfh) 1967{ 1968 __u32 *fh = vfh; 1969 __u64 inum = fh[2]; 1970 inum = (inum << 32) | fh[1]; 1971 return ino->i_ino == inum && fh[0] == ino->i_generation; 1972} 1973 1974static struct dentry *shmem_get_dentry(struct super_block *sb, void *vfh) 1975{ 1976 struct dentry *de = NULL; 1977 struct inode *inode; 1978 __u32 *fh = vfh; 1979 __u64 inum = fh[2]; 1980 inum = (inum << 32) | fh[1]; 1981 1982 inode = ilookup5(sb, (unsigned long)(inum+fh[0]), shmem_match, vfh); 1983 if (inode) { 1984 de = d_find_alias(inode); 1985 iput(inode); 1986 } 1987 1988 return de? de: ERR_PTR(-ESTALE); 1989} 1990 1991static struct dentry *shmem_decode_fh(struct super_block *sb, __u32 *fh, 1992 int len, int type, 1993 int (*acceptable)(void *context, struct dentry *de), 1994 void *context) 1995{ 1996 if (len < 3) 1997 return ERR_PTR(-ESTALE); 1998 1999 return sb->s_export_op->find_exported_dentry(sb, fh, NULL, acceptable, 2000 context); 2001} 2002 2003static int shmem_encode_fh(struct dentry *dentry, __u32 *fh, int *len, 2004 int connectable) 2005{ 2006 struct inode *inode = dentry->d_inode; 2007 2008 if (*len < 3) 2009 return 255; 2010 2011 if (hlist_unhashed(&inode->i_hash)) { 2012 /* Unfortunately insert_inode_hash is not idempotent, 2013 * so as we hash inodes here rather than at creation 2014 * time, we need a lock to ensure we only try 2015 * to do it once 2016 */ 2017 static DEFINE_SPINLOCK(lock); 2018 spin_lock(&lock); 2019 if (hlist_unhashed(&inode->i_hash)) 2020 __insert_inode_hash(inode, 2021 inode->i_ino + inode->i_generation); 2022 spin_unlock(&lock); 2023 } 2024 2025 fh[0] = inode->i_generation; 2026 fh[1] = inode->i_ino; 2027 fh[2] = ((__u64)inode->i_ino) >> 32; 2028 2029 *len = 3; 2030 return 1; 2031} 2032 2033static struct export_operations shmem_export_ops = { 2034 .get_parent = shmem_get_parent, 2035 .get_dentry = shmem_get_dentry, 2036 .encode_fh = shmem_encode_fh, 2037 .decode_fh = shmem_decode_fh, 2038}; 2039 2040static int shmem_parse_options(char *options, int *mode, uid_t *uid, 2041 gid_t *gid, unsigned long *blocks, unsigned long *inodes, 2042 int *policy, nodemask_t *policy_nodes) 2043{ 2044 char *this_char, *value, *rest; 2045 2046 while (options != NULL) { 2047 this_char = options; 2048 for (;;) { 2049 /* 2050 * NUL-terminate this option: unfortunately, 2051 * mount options form a comma-separated list, 2052 * but mpol's nodelist may also contain commas. 2053 */ 2054 options = strchr(options, ','); 2055 if (options == NULL) 2056 break; 2057 options++; 2058 if (!isdigit(*options)) { 2059 options[-1] = '\0'; 2060 break; 2061 } 2062 } 2063 if (!*this_char) 2064 continue; 2065 if ((value = strchr(this_char,'=')) != NULL) { 2066 *value++ = 0; 2067 } else { 2068 printk(KERN_ERR 2069 "tmpfs: No value for mount option '%s'\n", 2070 this_char); 2071 return 1; 2072 } 2073 2074 if (!strcmp(this_char,"size")) { 2075 unsigned long long size; 2076 size = memparse(value,&rest); 2077 if (*rest == '%') { 2078 size <<= PAGE_SHIFT; 2079 size *= totalram_pages; 2080 do_div(size, 100); 2081 rest++; 2082 } 2083 if (*rest) 2084 goto bad_val; 2085 *blocks = size >> PAGE_CACHE_SHIFT; 2086 } else if (!strcmp(this_char,"nr_blocks")) { 2087 *blocks = memparse(value,&rest); 2088 if (*rest) 2089 goto bad_val; 2090 } else if (!strcmp(this_char,"nr_inodes")) { 2091 *inodes = memparse(value,&rest); 2092 if (*rest) 2093 goto bad_val; 2094 } else if (!strcmp(this_char,"mode")) { 2095 if (!mode) 2096 continue; 2097 *mode = simple_strtoul(value,&rest,8); 2098 if (*rest) 2099 goto bad_val; 2100 } else if (!strcmp(this_char,"uid")) { 2101 if (!uid) 2102 continue; 2103 *uid = simple_strtoul(value,&rest,0); 2104 if (*rest) 2105 goto bad_val; 2106 } else if (!strcmp(this_char,"gid")) { 2107 if (!gid) 2108 continue; 2109 *gid = simple_strtoul(value,&rest,0); 2110 if (*rest) 2111 goto bad_val; 2112 } else if (!strcmp(this_char,"mpol")) { 2113 if (shmem_parse_mpol(value,policy,policy_nodes)) 2114 goto bad_val; 2115 } else { 2116 printk(KERN_ERR "tmpfs: Bad mount option %s\n", 2117 this_char); 2118 return 1; 2119 } 2120 } 2121 return 0; 2122 2123bad_val: 2124 printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n", 2125 value, this_char); 2126 return 1; 2127 2128} 2129 2130static int shmem_remount_fs(struct super_block *sb, int *flags, char *data) 2131{ 2132 struct shmem_sb_info *sbinfo = SHMEM_SB(sb); 2133 unsigned long max_blocks = sbinfo->max_blocks; 2134 unsigned long max_inodes = sbinfo->max_inodes; 2135 int policy = sbinfo->policy; 2136 nodemask_t policy_nodes = sbinfo->policy_nodes; 2137 unsigned long blocks; 2138 unsigned long inodes; 2139 int error = -EINVAL; 2140 2141 if (shmem_parse_options(data, NULL, NULL, NULL, &max_blocks, 2142 &max_inodes, &policy, &policy_nodes)) 2143 return error; 2144 2145 spin_lock(&sbinfo->stat_lock); 2146 blocks = sbinfo->max_blocks - sbinfo->free_blocks; 2147 inodes = sbinfo->max_inodes - sbinfo->free_inodes; 2148 if (max_blocks < blocks) 2149 goto out; 2150 if (max_inodes < inodes) 2151 goto out; 2152 /* 2153 * Those tests also disallow limited->unlimited while any are in 2154 * use, so i_blocks will always be zero when max_blocks is zero; 2155 * but we must separately disallow unlimited->limited, because 2156 * in that case we have no record of how much is already in use. 2157 */ 2158 if (max_blocks && !sbinfo->max_blocks) 2159 goto out; 2160 if (max_inodes && !sbinfo->max_inodes) 2161 goto out; 2162 2163 error = 0; 2164 sbinfo->max_blocks = max_blocks; 2165 sbinfo->free_blocks = max_blocks - blocks; 2166 sbinfo->max_inodes = max_inodes; 2167 sbinfo->free_inodes = max_inodes - inodes; 2168 sbinfo->policy = policy; 2169 sbinfo->policy_nodes = policy_nodes; 2170out: 2171 spin_unlock(&sbinfo->stat_lock); 2172 return error; 2173} 2174#endif 2175 2176static void shmem_put_super(struct super_block *sb) 2177{ 2178 kfree(sb->s_fs_info); 2179 sb->s_fs_info = NULL; 2180} 2181 2182static int shmem_fill_super(struct super_block *sb, 2183 void *data, int silent) 2184{ 2185 struct inode *inode; 2186 struct dentry *root; 2187 int mode = S_IRWXUGO | S_ISVTX; 2188 uid_t uid = current->fsuid; 2189 gid_t gid = current->fsgid; 2190 int err = -ENOMEM; 2191 struct shmem_sb_info *sbinfo; 2192 unsigned long blocks = 0; 2193 unsigned long inodes = 0; 2194 int policy = MPOL_DEFAULT; 2195 nodemask_t policy_nodes = node_online_map; 2196 2197#ifdef CONFIG_TMPFS 2198 /* 2199 * Per default we only allow half of the physical ram per 2200 * tmpfs instance, limiting inodes to one per page of lowmem; 2201 * but the internal instance is left unlimited. 2202 */ 2203 if (!(sb->s_flags & MS_NOUSER)) { 2204 blocks = totalram_pages / 2; 2205 inodes = totalram_pages - totalhigh_pages; 2206 if (inodes > blocks) 2207 inodes = blocks; 2208 if (shmem_parse_options(data, &mode, &uid, &gid, &blocks, 2209 &inodes, &policy, &policy_nodes)) 2210 return -EINVAL; 2211 } 2212 sb->s_export_op = &shmem_export_ops; 2213#else 2214 sb->s_flags |= MS_NOUSER; 2215#endif 2216 2217 /* Round up to L1_CACHE_BYTES to resist false sharing */ 2218 sbinfo = kmalloc(max((int)sizeof(struct shmem_sb_info), 2219 L1_CACHE_BYTES), GFP_KERNEL); 2220 if (!sbinfo) 2221 return -ENOMEM; 2222 2223 spin_lock_init(&sbinfo->stat_lock); 2224 sbinfo->max_blocks = blocks; 2225 sbinfo->free_blocks = blocks; 2226 sbinfo->max_inodes = inodes; 2227 sbinfo->free_inodes = inodes; 2228 sbinfo->policy = policy; 2229 sbinfo->policy_nodes = policy_nodes; 2230 2231 sb->s_fs_info = sbinfo; 2232 sb->s_maxbytes = SHMEM_MAX_BYTES; 2233 sb->s_blocksize = PAGE_CACHE_SIZE; 2234 sb->s_blocksize_bits = PAGE_CACHE_SHIFT; 2235 sb->s_magic = TMPFS_MAGIC; 2236 sb->s_op = &shmem_ops; 2237 sb->s_time_gran = 1; 2238#ifdef CONFIG_TMPFS_POSIX_ACL 2239 sb->s_xattr = shmem_xattr_handlers; 2240 sb->s_flags |= MS_POSIXACL; 2241#endif 2242 2243 inode = shmem_get_inode(sb, S_IFDIR | mode, 0); 2244 if (!inode) 2245 goto failed; 2246 inode->i_uid = uid; 2247 inode->i_gid = gid; 2248 root = d_alloc_root(inode); 2249 if (!root) 2250 goto failed_iput; 2251 sb->s_root = root; 2252 return 0; 2253 2254failed_iput: 2255 iput(inode); 2256failed: 2257 shmem_put_super(sb); 2258 return err; 2259} 2260 2261static struct kmem_cache *shmem_inode_cachep; 2262 2263static struct inode *shmem_alloc_inode(struct super_block *sb) 2264{ 2265 struct shmem_inode_info *p; 2266 p = (struct shmem_inode_info *)kmem_cache_alloc(shmem_inode_cachep, SLAB_KERNEL); 2267 if (!p) 2268 return NULL; 2269 return &p->vfs_inode; 2270} 2271 2272static void shmem_destroy_inode(struct inode *inode) 2273{ 2274 if ((inode->i_mode & S_IFMT) == S_IFREG) { 2275 /* only struct inode is valid if it's an inline symlink */ 2276 mpol_free_shared_policy(&SHMEM_I(inode)->policy); 2277 } 2278 shmem_acl_destroy_inode(inode); 2279 kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode)); 2280} 2281 2282static void init_once(void *foo, struct kmem_cache *cachep, 2283 unsigned long flags) 2284{ 2285 struct shmem_inode_info *p = (struct shmem_inode_info *) foo; 2286 2287 if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) == 2288 SLAB_CTOR_CONSTRUCTOR) { 2289 inode_init_once(&p->vfs_inode); 2290#ifdef CONFIG_TMPFS_POSIX_ACL 2291 p->i_acl = NULL; 2292 p->i_default_acl = NULL; 2293#endif 2294 } 2295} 2296 2297static int init_inodecache(void) 2298{ 2299 shmem_inode_cachep = kmem_cache_create("shmem_inode_cache", 2300 sizeof(struct shmem_inode_info), 2301 0, 0, init_once, NULL); 2302 if (shmem_inode_cachep == NULL) 2303 return -ENOMEM; 2304 return 0; 2305} 2306 2307static void destroy_inodecache(void) 2308{ 2309 kmem_cache_destroy(shmem_inode_cachep); 2310} 2311 2312static const struct address_space_operations shmem_aops = { 2313 .writepage = shmem_writepage, 2314 .set_page_dirty = __set_page_dirty_nobuffers, 2315#ifdef CONFIG_TMPFS 2316 .prepare_write = shmem_prepare_write, 2317 .commit_write = simple_commit_write, 2318#endif 2319 .migratepage = migrate_page, 2320}; 2321 2322static struct file_operations shmem_file_operations = { 2323 .mmap = shmem_mmap, 2324#ifdef CONFIG_TMPFS 2325 .llseek = generic_file_llseek, 2326 .read = shmem_file_read, 2327 .write = shmem_file_write, 2328 .fsync = simple_sync_file, 2329 .sendfile = shmem_file_sendfile, 2330#endif 2331}; 2332 2333static struct inode_operations shmem_inode_operations = { 2334 .truncate = shmem_truncate, 2335 .setattr = shmem_notify_change, 2336 .truncate_range = shmem_truncate_range, 2337#ifdef CONFIG_TMPFS_POSIX_ACL 2338 .setxattr = generic_setxattr, 2339 .getxattr = generic_getxattr, 2340 .listxattr = generic_listxattr, 2341 .removexattr = generic_removexattr, 2342 .permission = shmem_permission, 2343#endif 2344 2345}; 2346 2347static struct inode_operations shmem_dir_inode_operations = { 2348#ifdef CONFIG_TMPFS 2349 .create = shmem_create, 2350 .lookup = simple_lookup, 2351 .link = shmem_link, 2352 .unlink = shmem_unlink, 2353 .symlink = shmem_symlink, 2354 .mkdir = shmem_mkdir, 2355 .rmdir = shmem_rmdir, 2356 .mknod = shmem_mknod, 2357 .rename = shmem_rename, 2358#endif 2359#ifdef CONFIG_TMPFS_POSIX_ACL 2360 .setattr = shmem_notify_change, 2361 .setxattr = generic_setxattr, 2362 .getxattr = generic_getxattr, 2363 .listxattr = generic_listxattr, 2364 .removexattr = generic_removexattr, 2365 .permission = shmem_permission, 2366#endif 2367}; 2368 2369static struct inode_operations shmem_special_inode_operations = { 2370#ifdef CONFIG_TMPFS_POSIX_ACL 2371 .setattr = shmem_notify_change, 2372 .setxattr = generic_setxattr, 2373 .getxattr = generic_getxattr, 2374 .listxattr = generic_listxattr, 2375 .removexattr = generic_removexattr, 2376 .permission = shmem_permission, 2377#endif 2378}; 2379 2380static struct super_operations shmem_ops = { 2381 .alloc_inode = shmem_alloc_inode, 2382 .destroy_inode = shmem_destroy_inode, 2383#ifdef CONFIG_TMPFS 2384 .statfs = shmem_statfs, 2385 .remount_fs = shmem_remount_fs, 2386#endif 2387 .delete_inode = shmem_delete_inode, 2388 .drop_inode = generic_delete_inode, 2389 .put_super = shmem_put_super, 2390}; 2391 2392static struct vm_operations_struct shmem_vm_ops = { 2393 .nopage = shmem_nopage, 2394 .populate = shmem_populate, 2395#ifdef CONFIG_NUMA 2396 .set_policy = shmem_set_policy, 2397 .get_policy = shmem_get_policy, 2398#endif 2399}; 2400 2401 2402static int shmem_get_sb(struct file_system_type *fs_type, 2403 int flags, const char *dev_name, void *data, struct vfsmount *mnt) 2404{ 2405 return get_sb_nodev(fs_type, flags, data, shmem_fill_super, mnt); 2406} 2407 2408static struct file_system_type tmpfs_fs_type = { 2409 .owner = THIS_MODULE, 2410 .name = "tmpfs", 2411 .get_sb = shmem_get_sb, 2412 .kill_sb = kill_litter_super, 2413}; 2414static struct vfsmount *shm_mnt; 2415 2416static int __init init_tmpfs(void) 2417{ 2418 int error; 2419 2420 error = init_inodecache(); 2421 if (error) 2422 goto out3; 2423 2424 error = register_filesystem(&tmpfs_fs_type); 2425 if (error) { 2426 printk(KERN_ERR "Could not register tmpfs\n"); 2427 goto out2; 2428 } 2429 2430 shm_mnt = vfs_kern_mount(&tmpfs_fs_type, MS_NOUSER, 2431 tmpfs_fs_type.name, NULL); 2432 if (IS_ERR(shm_mnt)) { 2433 error = PTR_ERR(shm_mnt); 2434 printk(KERN_ERR "Could not kern_mount tmpfs\n"); 2435 goto out1; 2436 } 2437 return 0; 2438 2439out1: 2440 unregister_filesystem(&tmpfs_fs_type); 2441out2: 2442 destroy_inodecache(); 2443out3: 2444 shm_mnt = ERR_PTR(error); 2445 return error; 2446} 2447module_init(init_tmpfs) 2448 2449/* 2450 * shmem_file_setup - get an unlinked file living in tmpfs 2451 * 2452 * @name: name for dentry (to be seen in /proc/<pid>/maps 2453 * @size: size to be set for the file 2454 * 2455 */ 2456struct file *shmem_file_setup(char *name, loff_t size, unsigned long flags) 2457{ 2458 int error; 2459 struct file *file; 2460 struct inode *inode; 2461 struct dentry *dentry, *root; 2462 struct qstr this; 2463 2464 if (IS_ERR(shm_mnt)) 2465 return (void *)shm_mnt; 2466 2467 if (size < 0 || size > SHMEM_MAX_BYTES) 2468 return ERR_PTR(-EINVAL); 2469 2470 if (shmem_acct_size(flags, size)) 2471 return ERR_PTR(-ENOMEM); 2472 2473 error = -ENOMEM; 2474 this.name = name; 2475 this.len = strlen(name); 2476 this.hash = 0; /* will go */ 2477 root = shm_mnt->mnt_root; 2478 dentry = d_alloc(root, &this); 2479 if (!dentry) 2480 goto put_memory; 2481 2482 error = -ENFILE; 2483 file = get_empty_filp(); 2484 if (!file) 2485 goto put_dentry; 2486 2487 error = -ENOSPC; 2488 inode = shmem_get_inode(root->d_sb, S_IFREG | S_IRWXUGO, 0); 2489 if (!inode) 2490 goto close_file; 2491 2492 SHMEM_I(inode)->flags = flags & VM_ACCOUNT; 2493 d_instantiate(dentry, inode); 2494 inode->i_size = size; 2495 inode->i_nlink = 0; /* It is unlinked */ 2496 file->f_vfsmnt = mntget(shm_mnt); 2497 file->f_dentry = dentry; 2498 file->f_mapping = inode->i_mapping; 2499 file->f_op = &shmem_file_operations; 2500 file->f_mode = FMODE_WRITE | FMODE_READ; 2501 return file; 2502 2503close_file: 2504 put_filp(file); 2505put_dentry: 2506 dput(dentry); 2507put_memory: 2508 shmem_unacct_size(flags, size); 2509 return ERR_PTR(error); 2510} 2511 2512/* 2513 * shmem_zero_setup - setup a shared anonymous mapping 2514 * 2515 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff 2516 */ 2517int shmem_zero_setup(struct vm_area_struct *vma) 2518{ 2519 struct file *file; 2520 loff_t size = vma->vm_end - vma->vm_start; 2521 2522 file = shmem_file_setup("dev/zero", size, vma->vm_flags); 2523 if (IS_ERR(file)) 2524 return PTR_ERR(file); 2525 2526 if (vma->vm_file) 2527 fput(vma->vm_file); 2528 vma->vm_file = file; 2529 vma->vm_ops = &shmem_vm_ops; 2530 return 0; 2531} 2532